Recently, ink-jet recording systems, which enable simple and low-priced image formation, are applied to various printing fields, for instance, photography, various kinds of printing and special printing such as marking and color filters. In general, aqueous ink-jet inks composed of water as a main solvent are printed on dedicated paper provided with ink-absorptivity, but there have been put to practical use ink-jet recording systems other than aqueous type ones, for example, a phase change ink-jet system of using a solid wax ink at room temperature, a solvent type ink-jet system which uses an ink containing mainly a quick-drying solvent, and a actinic ray curing type ink-jet system.
Specifically, an ultraviolet-curing ink-jet system has recently been noted in terms of being relatively low-odor and quick-drying and enabling recording on a non-ink-absorptive recording medium, as compared to a solvent type ink-jet system, and there were disclosed various techniques of actinic ray curing type ink-jet recording.
There is practically used an actinic ray curing type ink-jet ink using a radical-polymerizable compound, typically, (meth)acrylate. Recently, there have also been proposed a actinic ray curing ink-jet ink using a cationic-polymerizable compound and an ink-jet printer by use thereof, based on the reason of adhesiveness to a recording medium, low-odor and reduced polymerization inhibition, as set forth in, for example, JP-A Nos. 2005-290246 and 2004-34543 (hereinafter, the term JP-A refers to Japanese Patent Application publication).
Further, in ink-jet printers, ink tanks and materials constituting an ink-supplying route between an ink tank and an ink-jet recording head often employ metals such as stainless steel and aluminum in terms of durability and simplicity in processing. Specifically, to remove impurities contained in an ink for prevention of plugging, there is provided a filter in the ink-supplying route, in which metals are employed as the material to constitute the filter.
It was proved that when performing image formation using a actinic ray curing ink-jet ink containing a cationic-polymerizable compound and an ink-jet printer constituted of the metals described above, precipitates are produced in the ink by working environment of the ink-jet printer and materials constituting the ink-supplying passage and the produced precipitates tend to clog the ink-supplying passage or reach the nozzle section, causing ejection troubles. Thus, the contact of a conductive material with a reactive conductive ink causes an undesired electrochemical reaction, resulting in formation of degradation products or polymeric products of ink constituents within the ink passage or an ink head, causing ejection troubles. For instance, when two kinds of metal members exist in the conduction state within the ink supply passage, contact of an ink with the metals forms a cell, giving rise to an electromotive force between the two kinds of metals, causing an electrochemical reaction accompanied with unexpected ink-curing (polymerization) reaction.
Further, when an alloy such as stainless steel is in contact with a conductive ink, the metal surface is not in a homogeneous state, resulting in microscopically conducting state between the metals and the ink, causing an electrochemical reaction on the metal surface.
In general, precipitation of actinic ray curing ink-jet is often due to leakage of actinic rays, against which there have been measures. However, there has been no description with respect to occurrence of precipitates due to transfer of electrons (electrochemical reaction) and there is no disclosure that such electron transfer can be controlled by component material or constitution of materials of ink-contact members.